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"Israel's Profound Choice on Iran"

In the end it will come down to Prime Minister Benjamin Netanyahu. His senior officials will make their cases, but he alone will have to make one of the most critical decisions in Israel's history: whether to attack Iran's nuclear program. I do not envy him.

There has been much media speculation lately about possible Israeli military action, largely from those who have never borne the crushing weight of momentous national decisions. Israel has made many controversial decisions over the decades, some mistaken. One thing that cannot be said is that it has taken major military action lightly. Rarely if ever have the stakes been higher.

The debate in Israel over the Iranian nuclear threat is narrow but critical nonetheless. No one in Israel disputes that a nuclear Iran would pose a dire threat to its security and that Israel should go to great lengths to prevent this from happening. Some believe that Iran is an extremist but essentially rational actor, and can thus be deterred. Others believe the threat to be truly existential — that Iran's theocratic commitment to Israel's destruction may lead it to take unimaginable steps and risks — and thus that Israel must do everything it can to prevent that.

Neither side can afford to be wrong. Netanyahu, by all indications of the existentialist mind-set, certainly cannot.

In this case, as in no other, it behooves critics of Israel generally and Netanyahu specifically to approach the issue with caution and humility. If one can legitimately argue whether a nuclear Iran truly is an existential threat to Israel, Netanyahu's perception of it as such is sincere.

Imagine him alone in his office, prior to the final decision: on the one hand, a threat to Israel's very existence, and the Jewish people have already undergone one Holocaust in recent history. Israel was established so that the Jewish people would never again face the threat of extermination. Never again.

Conversely, the consequences of acting are also potentially dire, even assuming a successful attack. Iran already has the technical means to produce a nuclear bomb, and an attack could set the program back by no more than a few years — of value in itself but not a solution.

Moreover, according to Israeli estimates, Iran has hundreds of Shahab missiles capable of striking Israel. And along with Syria, Iran has provided Hezbollah with an almost unfathomable arsenal of more than 50,000 rockets, designed precisely for this scenario, which can blanket all of Israel from Lebanon.

There is no reason to believe that Hezbollah will not use this arsenal. During the 2006 Lebanon war, Hezbollah fired 4,000 rockets at Israel, about one-third of its 13,000-missile arsenal at the time; if it were to employ a similar ratio today — and it could be far larger — the results would cause a level of destruction Israel has never before experienced. Hamas too has a large rocket arsenal in waiting, but "just" thousands.

Furthermore, the destabilization of the regimes in Egypt and Syria, following the Arab Spring, greatly increases the dangers that they too might be drawn into the confrontation. Syria, because it may have an interest in deflecting domestic unrest by focusing public attention on an external enemy. Egypt, because the new Islamist-based government will, at very best, be far less committed to peace with Israel. An explosion of popular fury on the Egyptian and Arab street may force it to act.

The international community, which is finally beginning to take serious measures to deal with the Iranian threat — nearly 20 years after Israel and the U.S. first began warning of it — will undoubtedly respond harshly to an Israeli action and in some cases even impose sanctions. The Obama administration has made clear that it firmly opposes military action, although its own measures have failed to address the threat. Israel has lived with international recriminations before, but it cannot afford an overly severe response from the U.S., its one major ally, on whom it would be even more dependent in a post-attack period.

So herein lies the dilemma: a potential risk to the nation's existence versus the uncertain results of military action, the likelihood of a devastating Iranian/Hezbollah response, the risk of an end to the peace with Egypt and even a military confrontation and regional war, severe international opprobrium and a partial rift with the United States.

Netanyahu alone will have to make the final decision. May he choose wisely.

Chuck Freilich, a senior fellow at Harvard's Kennedy School, was a deputy national security advisor in Israel during Labor and Likud governments.